• Journal of the Korea Computer Graphics Society
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• v.26 no.3
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• pp.69-77
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• 2020

This paper proposes an effective method of giving users feedback on 3-dimensional drawing and measures its performance to ensure that feedback can help users enter the correct position in 3D. In the experiment of drawing a given line shape using a hand-held controller, the user is provided with three levels of visual, auditory, and haptic feedback for the position input error. As a result of analyzing the position input accuracy according to the type of feedback, all types of feedback are able to significantly reduce errors, and visual feedback and haptic feedback are more effective than auditory feedback.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.447-454
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• 2007

본 논문에서는 사용자의 가상환경 내의 위치 정보에 대한 감각을 향상시키는 방법론으로서 햅틱 피드백(haptic feedback)과 사운드 피드백(sound feedback)의 모달리티를 활용한 그리드(grid)를 제안한다. 제안된 그리드는 사용자의 3차원 공간 내의 움직임(explorative procedure)에 추가적인 비 시각적인(non-visual) 위치정보 피드백을 부여하는데 그 목적을 두고 있다. 햅틱 모달리티를 활용한 3차원 그리드는 SensAble사의 PHANTOM(R) Omni$^{TM}$ 를 활용하여 설계되었으며, 사운드 모달리티를 활용한 경우 저주파 배경음의 주파수 특성(frequency characteristics of sound source)을 사용자 손의 공간 좌표값에 근거하여 재생 시의 표본 추출 비율(sampling rate)를 연속적으로 바꾸는 방식으로 설계되었다. 이러한 공간 그리드는 두 모달리티 각각의 독립적인 제시 및 동시 제시/제거를 통해 평가되었으며, 동시 제시의 경우 두 모달리티간의 어긋남(cross-modal asynchrony)이 없도록 설계되어 사용자의 공간 작업 시 모달리티간의 조화 (manipulating congruency)를 확보할 수 있도록 하였다. 실험을 통해 얻어진 결과는 그것의 통계적 유의미성을 분석하기 위해 다원변량분석과 사후검증(Turkey. HSD)을 거쳐 해석이 되었다. 공간 내 특정 좌표 선택을 기준으로 하는 그리드의 사용자 평과 결과, 3차원 내의 움직임에 대해 햅틱 및 사운드 피드백의 비 시각적 피드백은 사용자의 공간 작업의 오차를 줄여 주고 있음이 확인되었다. 특히 시각적인 정보만으로 확인하기 어려운 Z축 상의 움직임은 그리드의 도움으로 그 오차정도가 50% 이상 줄어 드는 것으로 확인되었다(F=19.82, p<0.01). 이러한 시각적 정보를 보존하는 햅틱, 사운드 피드백 방식을 HCI의 중요한 요소인 사용성과 유용성과 연관시켜 MMHCI(multimodal human-computer interaction) 방법론으로의 적용 가능성을 검토해 본다.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.542-545
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• 2009

본 연구는 2008년 3월부터 2009년 2월까지 S시 M동에 위치한 A청각장애인학교 학생 16명(초등학생 6명, 중학생 10명)을 대상으로 일상적 스트레스저항 능력에 뉴로피드백 훈련이 미치는 영향을 보고자하였다. 연구 결과는 다음과 같다. 첫째, 청각장애학생들의 스트레스 저항 능력에 뉴로피드백 훈련이 긍정적인 영향을 미쳤으며, 항스트레스(좌 우)가 통계적으로 유의하였다. 둘째, 청각장애학생들의 육체적 정신적 긴장 저항 능력에 뉴로피드백 훈련이 긍정적인 영향을 미쳤으며, 긴장도(좌 우)와 산만도(좌 우)가 통계적으로 유의하였다. 이상의 연구 결과를 종합해 볼 때 청각장애학생들의 일상적 스트레스 저항 능력에 뉴로피드백 훈련이 효과적인 중재임이 검증되었다. 따라서 본 연구 결과는 뉴로피드백 훈련을 통한 뇌기능 변화가 학생들의 육체적, 정신적 스트레스나 저항능력등의 객관적 지표로서 활용될 수 있는 가능성을 제시한 점에서 의의가 있으며, 이에 대한 경험적 증거의 축적을 위한 후속연구가 필요하다고 본다.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.285-290
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• 2013

The slotless linear synchronous motor(LSM) has the advantages that the structure of the mover is simple and it can control the trust force ripple by make the magnetic energy in a gap uniform by removing a slot of the primary iron core. Also, the application of the transportation system is becoming expansion because it high efficiency drive is possible and compares with the other LSM as control is more excellent. However, the application of the living field was unsatisfactory. Therefore, in this study, we examined the drive characteristics by the position feedback control for the living field application of the slotless LSM and we prove useful of the controller through load loading and the acceleration changing to get minimization of the speed vibration and stable answer characteristics.

• Management & Information Systems Review
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• v.36 no.3
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• pp.17-35
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• 2017

This study investigates the determinants of strategic positional change. Specifically, the study suggests performance feedback affects to a firm's strategic repositioning. Performance feedback is a concept that a firm decides whether success or not by comparing its performance relative to its aspiration level. Prior studies successively discover diverse behaviors. The study suggests three unexplored relationships between performance gaps and strategic positioning. First, when a firm's performance is below relative to its aspiration level, that firm's strategic position will be deviate from the industry norm. Second, as the degree of industrial density increases, the tendency that a firm's strategic position becomes deviate from the industry norm decreases. Third, when the degree of reference group's performance decreases, the tendency that a firm's strategic position becomes deviate from the industry norm decreases. For empirical analysis, this study examines data of 538 firms that in North America crude petroleum and natural gas industry. The result reveals that the direction of a firm's strategic change is shaped when firms' performance is below relative to aspiration level. Also, this relationship is moderated as industrial density changes or when reference groups' performance decreases. This study contributes to the current literature by explaining how a firms' strategic position is decided. Also, this study reveals that reference groups' performance could affect to organizational choice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2334-2340
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• 2010

Sun position computed by Michalsky shows maximum $1.5^{\circ}$, $0.88^{\circ}$ and 2 minutes differences in azimuth, altitude, and sunrise and sunset times respectively compared with Korean Almanac. The 2-axis solar tracking system, which consist control panel with ATmega128 CPU, BLDC motor-cylinder actuator and 2-axis link mechanism, was developed. Computed azimuth and altitude of sun for a current time, and latitude and longitude of tracker position built are controlled in real time by BLDC motor-cylinder actuators comparing with the position feed-backed by Hall sensor. The use of BLDC motor is free in maintenance. Implementation of a home-return function by Hall sensor is to minimize the cumulative error.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.1
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• pp.36-41
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• 2012

This paper presents torque control of DC motor using the velocity profile based acceleration/deceleration controller for automatic guided vehicles (AGVs). This technique has some advantage; to reduce the damage of motors and to extend the life time of motors. First, we generate velocity profiles for three cases and design the state feedback controller using the generated velocity profile as a reference. The state feedback controller has servo system for solving regulation problem. For the verification, we apply the proposed method to control a cart position and shows some simulation result.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.129-137
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• 2016

In the present study we verified performance of feed-forward control algorithm using short term prediction of ship motion information by taking advantage of developed numerical simulation model of FPSO motion. Up until now, various studies have been conducted about thrust control and allocation for dynamic positioning systems maintaining positions of ships or marine structures in diverse sea environmental conditions. In the existing studies, however, the dynamic positioning systems consist of only feedback control gains using a motion of vessel derived from environmental loads such as current, wind and wave. This study addresses dynamic positioning systems which have feedforward control gain derived from forecasted value of a motion of vessel occurred by current, wind and wave force. In this study, the future motion of vessel is forecasted via Brown's Exponential Smoothing after calculating the vessel motion via a selected mathematical model, and the control force for maintaining the position and heading angle of a vessel is decided by the feedback controller and the feedforward controller using PID theory and forecasted vessel motion respectively. For the allocation of thrusts, the Lagrange Multiplier Method is exploited. By constructing a simulation code for a dynamic positioning system of FPSO, the performance of feedforward control system which has feedback controller and feedforward controller was assessed. According to the result of this study, in case of using feedforward control system, it shows smaller maximum thrust power than using conventional feedback control system.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.9
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• pp.403-408
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• 2015

Kinect sensors have the ability to recognize the behavior and voice of the user. Due to its low-cost and high accessibility, Kinect sensors have been used in various fields, including healthcare, education and so on. In this paper, we propose to use Kinect in piano education. Specifically, the proposed method first recognizes the coordinate values of user's posture, compares them with coordinate values of teacher's posture and provide real-time feedbacks to the user. This enables user to keep the correct posture even when he is learning piano without a teacher. However, since the piano education is a long process, it is difficult to achieve the correct posture as a teacher immediately. Thus, we propose a user-oriented method to measure the error tolerance rate. The proposed method is the first feedback based piano education system that uses Kinect sensors.

• Progress in Medical Physics
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• v.25 no.2
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• pp.72-78
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• 2014

The aim of the study is to test a hypothesis that quasi-breath-hold (QBH) biofeedback improves the residual respiratory motion management in gated 3D thoracic MR imaging, reducing respiratory motion artifacts with insignificant acquisition time alteration. To test the hypothesis five healthy human subjects underwent two gated MR imaging studies based on a T2 weighted SPACE MR pulse sequence using a respiratory navigator of a 3T Siemens MRI: one under free breathing and the other under QBH biofeedback breathing. The QBH biofeedback system utilized the external marker position on the abdomen obtained with an RPM system (Real-time Position Management, Varian) to audio-visually guide a human subject for 2s breath-hold at 90% exhalation position in each respiratory cycle. The improvement in the upper liver breath-hold motion reproducibility within the gating window using the QBH biofeedback system has been assessed for a group of volunteers. We assessed the residual respiratory motion management within the gating window and respiratory motion artifacts in 3D thoracic MRI both with/without QBH biofeedback. In addition, the RMSE (root mean square error) of abdominal displacement has been investigated. The QBH biofeedback reduced the residual upper liver motion within the gating window during MR acquisitions (~6 minutes) compared to that for free breathing, resulting in the reduction of respiratory motion artifacts in lung and liver of gated 3D thoracic MR images. The abdominal motion reduction in the gated window was consistent with the residual motion reduction of the diaphragm with QBH biofeedback. Consequently, average RMSE (root mean square error) of abdominal displacement obtained from the RPM has been also reduced from 2.0 mm of free breathing to 0.7 mm of QBH biofeedback breathing over the entire cycle (67% reduction, p-value=0.02) and from 1.7 mm of free breathing to 0.7 mm of QBH biofeedback breathing in the gated window (58% reduction, p-value=0.14). The average baseline drift obtained using a linear fit was reduced from 5.5 mm/min with free breathing to 0.6 mm/min (89% reduction, p-value=0.017) with QBH biofeedback. The study demonstrated that the QBH biofeedback improved the upper liver breath-hold motion reproducibility during the gated 3D thoracic MR imaging. This system can provide clinically applicable motion management of the internal anatomy for gated medical imaging as well as gated radiotherapy.